var sTopBtn = document.getElementsByClassName('s-top-but')[0],
    header = document.getElementsByClassName('list-hd')[0]
addEvent(window, 'scroll', function() {
    var sTop = getScrollOffset().top;
    sTop ? sTopBtn.style.display = 'block' : sTopBtn.style.display = 'none'
})
addEvent(sTopBtn, 'click', function() {
    window.scrollTo(0, 0)
})
addEvent(header, 'click', function() {
    window.scrollTo(0, 0)
})